1. Field of the Invention
The invention relates to high voltage semiconductor devices, and in particular, to high voltage devices integrated with a Schottky diode device.
2. Description of the Prior Art
Double-diffused MOS (DMOS) transistor devices have drawn much attention in power devices having high voltage capability. The conventional DMOS transistor devices are categorized into vertical double-diffused MOS (VDMOS) transistor devices and lateral double-diffused MOS (LDMOS) transistor devices. Having advantages of higher operational bandwidth, higher operational efficiency, and convenience to be integrated with other integrated circuit due to its planar structure, LDMOS transistor devices are prevalently used in high operational voltage environment such as CPU power supply, power management system, AC/DC converter, and high-power or high frequency (HF) band power amplifier. The essential feature of LDMOS transistor device is a lateral-diffused drift region with low dope concentration and large area. The drift region is used to alleviate the high voltage between the drain and the source, therefore the LDMOS transistor device can have higher breakdown voltage.
When a LDMOS device integrated with a Schottky diode device is formed in an integrated circuit, the ON-resistance (RON), VSD and the reverse recovery charge (Qrr) of the LDMOS can be decreased. However, the integrated circuit accumulates more area, and decreasing the effective area of the LDMOS.